The present invention relates to a particle analyzer for detecting particles optically by passing particles of cells, blood corpuscles, or the like in a sheath flow, and a flow cell used therefor.
As the apparatus for analyzing particles in a sample such as cells and blood corpuscles, a so-called sheath flow system is widely known. In this system, by passing a sheath of liquid around the sample discharged from the a sample nozzle, the sample liquid can be reduced to a fine state in the flow cell. By optical measurement, apparent components in the sample can be measured and analyzed. The "sheath flow" refers to a flow covering or surrounding of the suspension of particles with a laminar flow liquid (sheath liquid), in order to arrange particles precisely in a row in the middle part of a minute aperture (a measuring liquid passage) to allow passage.
Hitherto, as a means to enhance the processing capacity of a flow cytometer, the apparatus disclosed in Japanese Laid-open Patent Hei. 2-176562 is known.
Having plural inlets for feeding a sample liquid, this apparatus is intended to lead the sample liquid into the flow cell from different passages, making it unnecessary to clean the sample liquid when changing over.
The prior art in this publication involves the following problems.
(1) Measurement of a sample an be started only after both sample liquids are led into their nozzle parts and prepared. This is because two nozzles are directed in the same way, and while measuring the sample liquid by passing from one nozzle, if it is attempted to introduce the other sample liquid into the other nozzle, this sample liquid may leak out of the nozzle. If leaking out of the nozzle occurs, it may run into the detecting region, which may give rise to a measuring error. Thus, unless the preparation of both sample liquids is complete, measurement cannot be started, and a shortening of the measurement time cannot be expected (in spite of the merit of simultaneous cleaning of both samples, a waiting time occurs if the two sample liquids are not prepared at the same time).
(2) It is difficult to manufacture double-structure nozzles.
(3) If merely two nozzles are provided, the flowing positions of the two sample liquids are different, and special measures would be required to keep the sheath liquids balanced, but moving the nozzles or moving the optical system as disclosed in the publication (to balance the sheath liquids would be practically impossible.